Design and Qualification of a Gimbal Suspension for Attitude Control System Testing of CubeSats
Masters Thesis Presentation by A. Holmberg
Time: Wed 2021-06-23 10.00 - 11.00
Lecturer: A. Holmberg
Since the dawn of the space race, satellites have grown rapidly in complexity and shrunk equally rapidly in size. Most of them contain an Attitude Determination and Control System on board for pointing and detumbling manoeuvres. These intricate systems are designed for an outer space environment, hence, phenomenon otherwise abscent in space such as gravity and aerodynamic drag present a challenge in validating these systems on Earth. The gimbal suspension testbed aims to provide a 3 degree of freedom suspension where the mounted satellite under test can rotate about either axis. The suspension induces disturbance torques that need to be modeled in order for the testbed to be characterized. This is accomplished by formulating the necessary gimbal dynamics, bearing frictional torque model, aerodynamic model and center of mass displacement model. This yields a relationship from which all torques present in the system can be expressed in terms of the angles, angular velocities and angular accelerations of the gimbal frames. Furthermore, the thesis covers the iterative design of the gimbal suspension and all of its constituents, the angular measurement method and a FEM simulation to estimate deformations. The result is presented in terms of a simulation that validates the models by predicting its behaviour for certain movement.